Re: Extract parameters from FIndFit output

• To: mathgroup at smc.vnet.net
• Subject: [mg107432] Re: Extract parameters from FIndFit output
• From: Bill Rowe <readnews at sbcglobal.net>
• Date: Fri, 12 Feb 2010 04:43:59 -0500 (EST)

```On 2/11/10 at 5:20 AM, fjl3rd at mac.com (Frank Letkiewicz) wrote:

>Is it possible to extract the parameter values generated from
>FindFIt to use in other operations?

>For example:

>xvalues = {3, 5, 12, 47, 81, 112, 129, 186}; yvalues = {0.05, 0.10,
>0.25, 0.50, 0.75, 0.90, 0.95, 0.99}; data =
>Partition[Riffle[xvalues, yvalues], 2]; fitLogNormal = FindFit[data,
>CDF[LogNormalDistribution[=CE=BC, =CF=83], x], {=CE=BC, =CF=
=83}, x]

>Out[396]= {=CE=BC -> 3.47733, =CF=83 -> 1.19773}

>Can I extract these =CE=BC and =CF=83 values in the output as
>regular numbers?

Whenever you get a replacement rule, the most direct way to
extract the values is to use it with ReplaceAll (./). For example,

In[9]:= xvalues = {3, 5, 12, 47, 81, 112, 129, 186};
yvalues = {0.05, 0.10, 0.25, 0.50, 0.75, 0.90, 0.95, 0.99};
data = Partition[Riffle[xvalues, yvalues], 2];
fitLogNormal =
FindFit[data, CDF[LogNormalDistribution[m, s],  x], {m, s}, x]

Out[12]= {m->3.47733,s->1.19773}

In[13]:= {m, s} /. fitLogNormal

Out[13]= {3.47733,1.19773}

Also, your method of combining xvalues and yvalues works but is
more complex than needed. Much simpler is

data=Transpose@{xvalues, yvalues};

=46or small data sets like you use here, there will be no
significant difference between what you did and using Transpose.
=46or very large data sets, Transpose will be faster.

```

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